xiedeyantu commented on PR #4785:
URL: https://github.com/apache/calcite/pull/4785#issuecomment-3850141405

   This SQL query actually comes from 
[CALCITE-6452](https://issues.apache.org/jira/browse/CALCITE-6452). Jira should 
currently be working correctly, but due to a cost model issue, it's selecting 
MergeJoin. From the DAG, it's clear that MergeJoin has about 7 fewer rows than 
HashJoin, but consumes 6 times more CPU. The current cost model ignores CPU 
usage, hence selecting MergeJoin. Although the cost model is flawed, this error 
should still be fixed.
   ```
   rel#207 (EnumerableHashJoin):
     rows=14.209999999999999
     cost={222.6832026146136 rows, 204.2 cpu, 0.0 io}
   
   rel#213 (EnumerableMergeJoin):
     rows=14.209999999999999
     cost={215.13639999999998 rows, 1272.3104732091813 cpu, 0.0 io}
   ```


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